Realitive dating

We take our samples back to the laboratory, and count the kinds of artifacts in them, and discover that each of the junkyards have broken pieces of musical recording methods in them--old broken records, pieces of stereo equipment, 8-track cassette tapes.

To start out, we will take a sample of the deposits in each of junkyards.

It isn't possible to investigate all of a junkyard, so we'll pick a representative sample of the deposit.

A good example of a change in artifact type is the development of hand-held PDAs from those first enormous cell phones. As an example of how change through time works, consider the different music recording methods that were used in the 20th century.

One early recording method consisted of large plastic disks which could only be played on a huge device called a gramophone.

But you would never have any 78s in junkyards closed before they were invented.

The same is true for 45s, and 8-tracks, and cassette tapes, and LPs, and CDs, and DVDs, and mp3 players (and really, any kind of artifact).When they became popularly available, you could find them everywhere; but then the technology changed and they became rare again. Archaeologists investigate trash, not shop window displays, so we measure things when they are discarded; in this example, we're going to use junkyards.Archaeologically, you would expect no 78s to be found in a junkyard that was closed before 78s were invented.For a study we're doing on, say, the availability of music in rural locations during the 20th century, we'd like to know more about the deposits in these illicit junkyards.Using seriation at our hypothetical junkyard sites, we will try to establish the chronology--the order in which the junkyards were used and closed.But nowadays we normally use who: This is George, who you met at our house last year.